If so, you probably felt a little off, even sick. Definitely not hungry.

The phrase off your feed was first used in the 1800s by farmers when their animals refused to eat. A cow who turned away from her hay, for example, would be said to be off her feed.

We can also find the phrase in the diaries of Captain R.F. Scott, the British explorer who, in 1911, set out for the South Pole. Scott brought along sled dogs and ponies, who proved essential to his campaign. Scott’s anguish when the ponies took ill comes through in his writing. Here are a few entries from his diary:

Thursday, June 15. Jimmy Pigg had an attack of colic this afternoon … on return to the stable he was off his feed. This evening the Soldier tells me he has eaten his food, so I hope all be well again.

Friday, July 14. We have had a horrible fright and are not yet out of the wood. At noon yesterday one of the ponies, “Bones,” suddenly went off his feed … Towards midnight I felt very downcast. It is so very certain that we cannot afford to lose a single pony …

Sunday, July 16. Another slight alarm this morning. The pony “China” went off his feed at breakfast time and lay down twice. He was up and well again in half an hour; but what on earth is it that is disturbing these poor beasts?

The ponies recovered, but perhaps their distress was a harbinger of what was to come. Scott eventually reached the pole, only to discover a Norwegian flag already marking the spot. Roald Amundsen, another explorer, had beat him there by five weeks.

Disheartened, Scott and his men began the march back to their base camp. They never made it. Waiting for a scheduled relief crew that never came, they perished in the frigid cold, wrapped in their sleeping bags. Scott’s diary was found tucked beneath his arm, inscribed with these final words: “It seems a pity, but I do not think I can write more. For God’s sake look after our people.”

Today, when we say people are “off their feed,” we’re not always talking about appetite. We often mean they’re just not acting like themselves. But what exactly is “off” is unclear; maybe it’s their feed.

So, that’s your tidbit for today. To be off your feed literally means to have lost your appetite; figuratively, it means that something indefinable is not quite right.